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UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THEVVESTERN IELECTRIC COMPANY, OF SAME PLACE.

TELEPHONE-EXCHANGE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 543,901, dated August6, 1895.

A li atio fil d November 12, 1894. Serial No. 528,527. (No model.)

To aZZ whom it may concern: branches of the line at the sub-station,one, Be it known that 1, CHARLES E. SCRIBNER, at least, of which mustalways be closed. In

a citizen of the United States, residing at Chiorder to conform to therequirements of either cago, in-the county of Cook and State of Illiofthe methods of automatic signaling de- 5 nois,have invented a certainnew and useful scribed, one of these branches must be con- Improvementin Telephone-Exchange Sysstructed of great resistance, so as topractitems, (Case No. 364,) of which the following cally open theline-circuit. The expense of is afull, clear, concise, and exactdescription, the system is thus increased while its effi- 6c referencebeing had to the accompanying ciency is somewhat reduced.

I0 drawing, forming a part of this'specification. In my invention hereinI have aimed to ac- Myinvention relatesto signaling appliances complishthe automatic transmission of the for telephone-exchange systems, itsobj ectbe required signals without making the branches ing to produce anew organization in which containing the signaling telephonic applithevarious necessary signals from the subances of Widely-differentresistances.

:5 station to the central station may be trans- In myinvention Iprovidemeans at the submitted automatically in the use of the substation formomentarilyinterrupting the curstation telephone. rent in theline-circuit, and any annunciator It is usual in telephone-exchangesystems or signaling device in the line at the central to provide eachsub-station with a device for station adapted to display its signal inre- 20 transmitting the call or initial signal to the spouse to aninterruption of the current central station to indicate to the attendantthrough it. In order to prevent the immeoperator that a connection isdesired, and also diate elfacing of the signal at the central statotransmita disconnection-signal to indicate tion, I construct theannunciator with switchto the operator that an established connectioncontacts connected to open the circuit through 25 is no longer required.-These signals have it when the signal is displayed. I have alsosometimes been transmitted automatically, combined with the line-circuitand annunciavarious devices having been employed for this tor anauxiliary or local circuit adapted to purpose. Of these the most commonorganibe closed in the act of making connection zation hascomprisedasource of current at the with the line, in response to a call,to effect 0 central station connected with each telephonethe resettingof the annunciator, or to retain line through an individual or lineannunciait inoperative independently of the continuity tor, thecontinuity of the circuit being conof the line-circuit when connectionis made trolled at the sub-station by suitable switchwith the line incompliance with an order contacts in connection with the automatic froma different subscriber. Suitable clear- I 5 telephone-switch. In someinstances these ing-out annunciators constructed in the sameswitch-contacts have acted to open the linemanner and also adapted to beoperated by circuit, retaining it discontinuous as to curtheinterruption of the line-circuit are emrents of constant directionduring the use of ployed in connection with the plug-circuit for thetelephone, the annunciator being in this uniting diiferent subscriberslines.

' 40 case adapted to display its signal upon and My invention comprisesthen, in general, during the interruption of current through its meansat the sub station for momentarily magnet. In other forms theswitch-contacts breaking the line-circuit, an annunciator in have actedto close the circuit during the use the line adapted to respond to suchan inter of the telephone, the annunciator being arruption, and, havingresponded, to open its 5 ranged to respond to its current through coils.circuit to prevent its re-energization, together It will be understood,however, that in pracwith a source of current in the line, a local ricethe circuit of the telephone-line must circuit for resetting theannunciator when be closed at the sub-station as to current ofconnection is made with the line, and clearsome character in order topermit communiing-out annunciators adapted to be operated 5o cation bysignals or by means of the telephone by a final interruption of theline-circuit upon from the central station to the sub-station. thecompletionof conversation.

This has necessitated the employment of two My invention is illustratedin the accompanying drawing. Therein two sub-stations A and A arerepresented connected by means of lines 1 and 2, respectively, with theswitching and signaling appliances at the central station, together withplugs and accessory apparatus provided for the operator in connectingthe ditferent lines.

The apparatus at the sub-station comprises the usual telephone a andtransmitter a and the signal-bell a in separate branches from theline-circuit, and a telephone switch-hook a [or automaticallyestablishing connection with the telephonic or signaling appliances whenthe telephone is removed from or replaced upon the switch-hook. Thisswitch is constructed to effect a momentary break in the line-circuit asit passes from one position to the other.

The line-conductor 1 connects at the central station with theline-spring b of a springjack 0 upon a telephoneswitchboard, and

with one terminal of a line-annuneiator (Z, whose other terminal isgrounded through a battery 6, which is common to all the lines at theexchange. The annuneiator d comprises a magnet 01 and an armature dtherefor, which is pivoted atits lower edge, so as to fall outward whenunattracted by the magnet. Before the armature is pivotally suspended alight shutter or shield d in position to be struck by the armature d inits outward movement and to be thrown into aliori- Zontal position,thereby disclosing a number or other indication painted on the face ofarmature d This armature carries a light spring (1 which is adapted tocross together two contact-points d 61 when the shutter is attracted.These contact-points are included in the line-conductor between theline-wire and the annunciator d.

The spring-jack 0 comprises, in addition to the line spring 17, atubular thimble b',which is connected by a conductor 3 with thelineterminal of annunciator d.

The connecting-plug, as f, is adapted to make connection with both theline-spring b and the thimble Z). The two plugs fand f of a pair areunited through a conductor 4. This conductor includes two calling-keys7t and 7t, and is rendered discontinuous as to currents of constantdirection by the interposition in it of a condenser Two clearing-outanunnciators 7c and 7c are employedone in a branch5 and the other in abranch 6 from conductor 4 on eitherside of condenser i-the branchesbeing connected by a common conductor 7 with the free pole of battery 0.

The calling-keys h and h are of peculiar construction, having, inaddition to the usual contacts, a pair of switch connections comprisinga spring Z and its anvil Z. The anvil Z is grotmded,while the springl isconnected with the conductor, including the corresponding clearing-outannunciator. Either key acts to disconnect the tip of the correspondingplug from the other plug and to connect it with one terminal of agenerator 171. of signalingcurrent, and at the same time to close thecircuit of the corresponding annunciator to earth.

The usual listening-key n is provided for the operator to form aconnection between the conductor 4 and her telephone-set 0.

Having thus described the mechanism and circuits of my invention, I willtrace its operation.

In the normal condition of the apparatus current from the battery 6finds circuit through annunciator d and its switclrcontacts d d 'to line1,and thence thronghswiteh a and bell a to earth at the sub-station.Magnet (1 of the annunciator is excited and retains the armature d inits upright position, the shutter 61 concealing the indication on theface of the armature.

Assuming that subscriber at station A wishes to communicate withsubscriber at station A, he removes the telephone a. from itsswitch-hook, which rises to close the circuit through the telephone andthus momentarily interrupts the current flowing in line 1. During thisinterruption of the current the magnet dof annnnciator cl loses itsmagnetism and releases armature (1 In its first outward movement thisarmature removes the circuit connection between contacts cl (1, thusopening the line-circuit at the aniiunciator, and in its subsequentmovement it raises the shield d and discloses the iurlication on theface of the armature (1, thus signifying to theopcrator that connectionis desired by the subscriber calling. The operator observing this,inserts plugf into springjack 0. Line circuit 1 is thus extended,through the medium of spring I) and plug f, to the conductor 4 of theplug-circuit, and

thence, key it having been depressed, to the operators telephone-set 0,and the subscriber gives his order orally for the desired connection.

By the insertion of plug fin the springjack the thimble b is connectedwith line 1, whereby a circuit is provided from battery 0 through magnetd to the line. The magnet 01' is again excited and retracts armature (leifacing the signal and again closing contacts d cl together. It mayalso be noted that circuit is provided from battery 6 throughconductor7, clearing-out annunciator 7c, and conductor 5 to the plugf,and thence to earth at the sub-station, whereby the clearing-outannuneiator is placed in readiness to respond to any interruption of theline-circuit, and hence to indicate the replacement of tele phone a uponthe switch-hook after the completion of conversation.

Having received from subscriber at station A his order for connectionwith sub-station A, the operator inserts plug f into spring jack o ofthat line and depresses calling-key h to connect the signaling-generatorm with the line. Since the piece I) of spring-jack c is connected withthe line, circuit through the annunciator of line to station A isthereby completed and this annunciator is prevented from respondingeither to the signaling-current, which may find circuit through it, orto the subsequent interruption of the line-circuit when the telephone atstation A is removed from the switch-hook.

It will be observed also that during the operation of signaling by meansof key h, a temporary circuit is created through clearingout annunciatorso that the latter is not released and does not disclose its indicationduring the'interruption of conductor 4 at the signaling-key. When thesubscriber at station A responds to the call-signal and removes histelephone from the switch-hook, the circuit from battery e throughclearing-out annunciator 70' to earth at the sub-station is momentarilyinterrupted and the clearing-out annunciator displays its signal. Thisis not, however, interpreted as a signal for disconnection, butindicates to the operator who has just completed the connection with thesubscriber at that station that he is in communication with thecalling-subscriber. The operator, therefore, replaces the signal withoutwithdrawing the cords from the other springjacks. Similarly if eithersignal should be alone operated at any time during the existence of theconnection this will indicate to the operator that the correspondingsubscriber had replaced his telephone on its switch-hook, but thatconversation has not yet been finished since the other subscriber isstill at his telephone; but it both signals were operated this wouldindicate that both subscribers, having terminated their conversation,had replaced their telephones on their switch-hooks. The operator would,therefore, proceed to disconnect the lines by Withdrawing the plugs fand f from the springjacks.

Having thus described my invention and its mode of operation, I claim asnew and desire to secure by Letters Patent- 1. The combination with atelephone line, of an an nunciator and a battery normally included inthe circuit of said line at the central station, a switch at thesubscribers statiou adapted to open the circuit of said line, and a pairof contact points in said line normally connected together, controlledby said annunciator and adapted to be opened to disconnect saidannunciator from the line when the circuit of said line is interruptedby the of an annunciator and battery normally in circuit therewith atthe central station, a switch at the subscribers station for opening thecircuit of said battery, contacts controlled by said annunciator adaptedto be opened when the circuit of said battery is interrupted, and switchcontacts closed together in the act of making connection with the lineadapted to bridge the interruption of the circuit at the annunciator torestore the annunciator.

3. The combination with a telephone line, of an annunciator and abattery normally in circuit with said line at the central station,contacts controlled by said annunciator adapted to be opened when thecircuit through said annunciator is interrupted, said line beingprovided at the subscribers station with two branches of substantiallyequal resistance, one of said branches containing the telephonicapparatus and the other the calling apparatus, and a switch adapted toalternately include said branches in circuit with the line, and tomomentarily open the circuit of said battery by the act of changing theconnection through said branches.

4. The combination with a telephone line, of an annunciator and abattery in the line,

contact points controlled by the annunciator adapted to open the circuitthrough the annunciator when the magnet of the annunciator is unexcited,a springjack for the line, and

contact points therein adapted to be closed together when a plug isinserted in the springjack and to again connect the annunciator with theline, and means for interrupting the line circuit at the subscribersstation to operate the annunciator, substantially as described.

5. The combination with a telephone line, of means for interrupting theline circuit at the substation, a battery in the line at the centralstation, two annunciators in parallel branches of the circuit at thecentral station, each having contact points controlled by it adapted toopen the circuit through it when the current through it is interrupted,and a circuit formed temporarily in the springjack, bridging the switchcontacts of one of the annunciators, substantially as described.

In witness whereof I hereunto subscribe my name this 8th day ofNovember, A. D. 189;.

CHARLES E. SORIBNER. Witnesses:

ELLA EDLER, FRANK R. MCBERTY.

